ABSTRACT
A theory is presented to explain why early hominins were able to adapt and survive in a variable climatic habitat without a permanent hairy coat. The three main factors which may have influenced this important evolutionary development are discussed. First of all, an aquatic diet rich in essential lipoproteins provided increased intellectual processing; the second was the discovery of fire which meant that they could rely on an external source of heat when needed; and the third was improved manual dexterity. This meant that they could make their own coat, using or dispensing with it depending on their activity and the climatic conditions.
Desmond Morris describes the aquatic hypothesis as ‘an ingenious theory’. Other scientists have pointed out that a hominin walking and hunting on the open savannah would generate a great deal of endogenous heat, in addition to the heat of the sun, and that bipedalism ‘must have evolved for some other reason’. Other logical explanations are given to demonstrate that changes in human skin could only have been a result of exposure to a semi-aquatic, and not a savannah habitat.
The significance of the gene which determines skin colour pigment is discussed. The brown-black pigment, Eumelanin, which provides vital protection from U/V light is almost universal in tropical and sub-tropical countries, but Pheomelanin, which is pale and non-protective, is found in other climates. An explanation is given why the pale skin of primates, including early ancestral humans, changed to a dark colour during hominin evolution, but when humans moved to other cooler climates, mutations occurred to produce lighter skin. The cause and incidence of skin cancers and melanomas are discussed and its significance for African albinos explained. (279 words)
